I might be having a moment here but I want to make sure before I try to help you.. and maybe it doesn't make a difference ... but are you putting the transfer on buttercream or a whipped icing?? When I think of "whipped" icing, I think of something that might be cool whip based, or a seven minute type frosting?? Buttercream is a heavier consistency and more stable...
Sorry if I am being off the mark here!!! I just want to make sure which one you are planning on using!!!! 
I used to buy mine from Kopykake and they are not meant for whipped cream icing (dairy or not, like rich's). Once I got an order for a 3 milk cake which would very extremely sweet with buttercream so I told the customer that I couldn't put any pictures on it if it had the rich's bettercream, she said do it anyway. It was a photo with green accents (like camo) and when I delivered it the photo was very dark, almost black, because the ink was bleeding and the icing sheets were melting on the bettercream. So I don't do it anymore.
The picture of the cake is not that good but you can see the photo ended up very dark.
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